In recent years, with a significant increase in the amount of information on movie images, computer images and the like, various devices have been used to transmit a baseband signal such as a millimeter wave at a high speed. For such a high speed baseband signal transmission device, it is necessary to transmit a high speed baseband signal such as a millimeter wave with no error.
Meanwhile, according to a semiconductor package for transmitting a baseband signal, there are many cases in which a semiconductor chip including a plurality of circuit elements formed on a semiconductor element to constitute a large-scale electronic circuit is sealed into a small package provided with a plurality of terminals.
FIG. 38A is a plan view illustrating a configuration example of a semiconductor package 1 according to the related art, and FIG. 38B is a sectional view taken along line X3-X3 of FIG. 38A. The semiconductor package 1 illustrated in FIG. 38A includes a semiconductor chip 2 and an interposer substrate 4.
The semiconductor chip 2 is mounted on the interposer substrate 4 and includes an electrical circuit for transmitting a baseband signal. The semiconductor chip 2 is provided on the surface thereof with a plurality of pad electrodes 3. The interposer substrate 4 is provided on the rear surface side thereof with a plurality of terminal electrodes 5. The terminal electrodes 5 are terminals for an electrical connection with a mounting substrate to which the semiconductor package 1 is applied, and are used for a power source, grounding, and inputting/outputting an electrical signal. The interposer substrate 4 connects the pad electrodes 3 of the semiconductor chip 2 to the terminal electrodes 5. The pad electrodes 3 of the semiconductor chip 2 are connected to lead electrodes 6 by bonding wires 7.
Furthermore, the interposer substrate 4 is provided on the surface thereof with the lead electrodes 6 corresponding to the pad electrodes 3. The lead electrodes 6 are connected to the terminal electrodes 5 via wiring patterns in the interposer substrate 4. In general, in order to connect the semiconductor chip 2 to the interposer substrate 4, lead frames or the bonding wires 7 are used. Otherwise, there is a flip-chip bonding method using solder balls. According to the flip-chip bonding method, protrusion electrodes 9 (bumps: solder balls) are provided on the rear surface of the semiconductor chip 2 and the surface of the interposer substrate 4, and the semiconductor chip 2 is bonded to the interposer substrate 4 via the solder balls.
The semiconductor chip 2 and the bonding wires 7 mounted on the interposer substrate 4 are sealed with a molded resin 8. The molded resin 8 is a dielectric material, and the main sealing purpose is to protect the semiconductor chip 2 in the package and wirings using the bonding wires 7. The semiconductor package 1 is normally mounted on the surface of a mounting substrate such as a printed board for use. The semiconductor package 1 is wired to the same printed board or an electrical circuit of another printed board.
In general, in the wiring in a printed board, there are many cases in which a multilayer substrate is used with an increase in the number of wirings. The multilayer substrate is formed by patterning wirings on a thin dielectric substrate, bonding the wirings to one another in an overlapped state, and connecting wirings of each layer to one another through vias. In layers of the multilayer substrate, connectors are mounted on each dielectric substrate, and wiring is performed through a direct connection among the connectors or a cable connection among the connectors.
FIG. 39 is a sectional view illustrating a configuration example of an electronic device 700 including stacked semiconductor packages 1a and 1b. According to the electronic device 700 illustrated in FIG. 39, a housing 12 includes the two semiconductor packages 1a and 1b, mounting substrates 10a and 10b, a chassis 11, connectors 14, and cables 15.
The semiconductor package 1a is mounted on the lower substrate 10a and the semiconductor package 1b is mounted on the upper substrate 10b. The semiconductor packages 1a and 1b are bonded to the chassis 11 so that the surfaces of the semiconductor packages 1a and 1b are brought into contact with the chassis 11. This allows heat generated from the semiconductor packages 1a and 1b to be discharged to the chassis 11. The two substrates 10a and 10b are fixed to the chassis 11. The chassis 11 is further fixed to the housing 12. For the fixing of the substrates 10a and 10b to the chassis 11 and the fixing of the chassis 11 to the housing 12, a screw structure 13 is employed. As a material of the chassis 11, a metal, a solid plastic material and the like are used. Furthermore, data transmission between the semiconductor packages 1a and 1b is performed by providing the connectors 14 to the lower substrate 10a and the upper substrate 10b and connecting the connectors 14 to each other using the cables 15.
In relation to such an electronic device 700 for transmitting/receiving a millimeter signal, Patent Literature 1 discloses a dielectric waveguide line. According to the dielectric waveguide line, a pair of main conductor layers, via hole groups of two rows, and a sub-conductor layer are provided, and the main conductor layers are formed in parallel to each other with the dielectric interposed therebetween. The via hole groups are formed to allow the main conductor layers to be electrically connected to each other at an interval equal to or less than a cut-off wavelength in a signal transmission direction. The sub-conductor layer is connected to the via hole groups and is formed in parallel to the main conductor layers. In the dielectric waveguide line, when transmitting an electrical signal by a waveguide area surrounded by the main conductor layers, the via hole groups, and the sub-conductor layer, at least one of the main conductor layers is formed with a slot hole for electromagnetic coupling with a high frequency transmission line. The high frequency transmission line includes a microstrip line and is formed at a position facing the slot hole. When the dielectric waveguide line is formed as described above, the dielectric waveguide line can be easily electromagnetically coupled with another high frequency transmission line, and signal transmission is possible. In addition, it is possible to provide a waveguide line having stable characteristics from microwaves to millimeter waves.